Wild form of rye reduces wheats yield, affects its quality
By MATTHEW WEAVER
A wild form of rye is causing quality to decline in Washington's winter wheat crops.
Washington State University Extension weed scientist Joe Yenish said cereal rye is impacting fields in Eastern Washington's intermediate- and low-rainfall areas, from Davenport to Dusty and westward.
Cereal rye is the feral type of the rye grown as a crop.
The total acreage and the intensity of the infestation varies from field to field, Yenish said.
One measure of control is to switch from a winter crop to a spring crop. Cereal rye is nearly exclusive to winter wheat and other winter crops as a winter annual.
The rye reduces the wheat's yield but, more importantly, it affects quality, Yenish said.
"The rye is considered foreign material and the dockage gets very severe on that," he said. "Secondary to the grain being in the harvested wheat, you get into situations like ergot, the fungal body that replaces the grain."
Ergot is toxic and reduces the value of any grain it shows up in, Yenish said.
Cereal rye is spread through contaminated equipment and saved seed. There are differing schools of thought on whether wildlife also spreads the weed, he said.
"Once it sets seed, that seed survives for a very long time in the soil," he said. "It's not enough to just have it one year and do a lot of roguing. That practice needs to be continued over several years, if not decades."
The herbicide Beyond, used on Clearfield wheat -- the only way the herbicide can be applied -- has shown more than 90 percent control of cereal rye. But Yenish said it requires higher application rates and is expensive. He recommends split applications in the fall and spring to get some assurance of control.
For farmers with isolated infestations, Yenish recommends harvesting the rest of the field first, leaving the patches for the last. Equipment can be cleaned later and those loads will take dockage hits, but dockage will be limited and clean grain will remain clean.
Some fields are so heavily infested that populations need to be brought down to manageable levels to effectively control it with herbicides. Yenish said that can be done with more spring cropping, more intensive management post-harvest and trying to manage the cereal rye by germinating it into a plant from a seed, making it easier to kill through tillage or glyphosate application.
Some farmers are experimenting with use of winter broadleaf crops like canola, which opens up the possible application of Roundup for Roundup Ready canola or Assure II, Select Max or Poast for non-Roundup Ready canola for weed control.
The crop is a problem over most cereal-producing areas. Yenish said Colorado has a very severe infestation where winter wheat is continuous or rotations are limited, similar to the Northwest.
"The more frequently the wheat is grown, the more prevalent the cereal rye becomes a problem," he said.
It's hard to say whether the trend could be long term, although Yenish hopes not. A background population has been established that will always be present if favorable environmental conditions continue.
"Hopefully it's just a short run in terms of the problem and won't lead to larger infestations in the long run," he said.